Eighteen Church of England bishops have criticised the Government's welfare reforms.

In a letter to The Observer, they wrote that they felt "compelled to speak for children" in response to a planned £500-a-week benefits cap for families as part of the Welfare Reform Bill. The bishops are concerned that the policy will leave children facing "severe poverty and potentially homelessness".

They are supporting a series of amendments to the bill - set to be debated in the House of Lords on Monday - which have been tabled by the Bishop of Leeds and Ripon, John Packer and drawn up with the help of the Children's Society.

According to The Observer their message has been backed by the Archbishop of Canterbury and the Archbishop of York.

Bishop Packer told the newspaper: "I think it is the care for children which is particularly important to me in this whole debate about welfare and about the way in which people are treated in our society."

The Children's Society has warned that a cap on the total benefits households can claim could make more than 80,000 children homeless and push many thousands more into poverty.

It has proposed that the bill should be altered to remove child benefit from household income for the purposes of calculating the level of the cap. The charity also put forward the option of removing certain vulnerable groups from the cap, and providing a grace period for newly unemployed families.

The bishops wrote: "The Church of England has a commitment and moral obligation to speak up for those who have no voice.

"As such, we feel compelled to speak for children who might be faced with severe poverty and potentially homelessness, as a result of the choices or circumstances of their parents. Such an impact is profoundly unjust."

The letter was signed by the bishops of Bath and Wells, Blackburn, Bristol, Chichester, Derby, Exeter, Gloucester, Guildford, Leicester, Lichfield, London, Manchester, Norwich, Oxford, Ripon and Leeds, St Edmundsbury and Ipswich.